A wind turbine rotor blade is usually made of a reinforced fiber material, and is constructed by laying up a suitable fiber arrangement in two mold halves (one for the suction side of the blade and one for the pressure side of the blade). In the known methods, the fiber layup is infused with a resin to bond the fiber and fiber layers and then cured to harden in a vacuum-assisted resin transfer molding (VARTM) technique. The blade halves are joined, and the outer surface of the blade can be treated as necessary.
The desired aerodynamic shape of a wind turbine rotor blade airfoil, the inclusion of a circular root section for connection to a hub, and the requirements of lightness as well as structural strength all add up to a costly and complex manufacturing process. For example, the process of laying out fiber material manually in the blade mold is very time consuming, leading to a lengthy total production time of a blade. Furthermore, manual layup is difficult and even if great care is taken, faulty positioning of the fiber material cannot be ruled out. Inconsistencies in the fiber layup—for example too thin or too thick fiber layers, over-tensioned or under-tensioned fiber rovings, wrinkles or creases in the fiber material etc.—can lead to structural deformities in the finished rotor blade.
Different regions of a wind turbine rotor blade are subject to different types of loading during operation, and some regions of the blade are subject to greater loading than other regions. A certain minimum material thickness is therefore necessary in order to avoid cracks developing in the blade. However, an increase in material thickness will result in an increase in the weight of the blade. In conventional manufacturing techniques, the fiber material layup may not properly consider these factors, so that the resulting blade may not exhibit the necessary structural strength, or the blade may be excessively heavy so that handling during transport and installation is made more difficult and time-consuming.